1. Field of the Invention
This invention relates to a piston type compressor that is used for a car air conditioner, for example, and compresses a refrigerant gas by the reciprocating motion of pistons.
2. Description of the Related Art
A double-headed piston-type compressor shown in FIGS. 6 and 7 of the accompanying drawings is known as a compressor of this kind.
A pair of cylinder blocks 101 and 102 are mutually joined and fixed at their opposed end portions as shown in FIG. 6. A front housing 103 is joined and fixed to the end portion of the cylinder block 101 on the front side (on the left side in the drawing). A rear housing 104 is joined and fixed to the end portion of the cylinder block 102 on the rear side (on the right side in the drawing). A drive shaft 105 is rotatably supported in such a fashion as to extend from the cylinder blocks 101 and 102 to the front housing 103. A plurality of cylinder bores 106 are formed round the axis L of the drive shaft 105 in each cylinder block 101, 102. A double-headed-type piston 107 is accommodated in each cylinder bore 106 and is connected to the drive shaft 105 through a swash plate 108.
A suction chamber 109 is defined on the outer peripheral side of each of the housings 103 and 104 as shown in FIG. 7. A discharge chamber 110 is defined on the inner peripheral side of the suction chamber 109 in each of the housings 103 and 104. Though FIG. 7 shows the rear housing (104) side, the construction is substantially similar on the front housing (103) side, too.
Turning back again to FIG. 6, a valve/port-forming member 111 is clamped between each of the cylinder blocks 101, 102 and each of the housings 103, 104. The valve/port-forming member 111 has a suction port 112 and a suction valve 113 that are interposed between each cylinder bore 106 and the suction chamber 109, and a discharge port 114 and a discharge valve 115 that are interposed between each cylinder bore 106 and a discharge chamber 110, respectively. A plurality of discharge valves 115 are so formed as to extend in a radial direction (in the direction of the corresponding discharge port 114) from the outer edge portion of a disc-like substrate 116 (see FIG. 7).
The rotational motion of the drive shaft 105 is converted to the reciprocating motion of the piston 107 through the swash plate 108. In consequence, a series of compression cycles of suction of the refrigerant gas of the suction chamber 109 into the cylinder bores 106 through the suction port 112 and the suction valve 113, compression of the refrigerant gas that is sucked, and discharge of the compressed refrigerant gas to the discharge chamber 110 through the discharge port 114 and the discharge valve 115 are repeatedly carried out. The refrigerant gas discharged to the discharge chamber 110 is exhausted to an external refrigerating circuit.
Inside each housing 103, 104, the retaining portion 117 comprises a ring-like wall body, as shown in FIG. 7, and is formed in such a fashion as to extend into the discharge chamber 110. The retaining portion 117 retains a ring-like area in the center portion of the valve/port-forming member 111 by its distal end surface 117a (FIG. 6). The valve/port-forming member 111 comprises a laminate of a plurality of sheet materials, and its outer peripheral side is clamped directly by the cylinder block 101, 102 and the housing 103, 104. If this retaining portion 117 is not disposed, the center portion of the valve/port-forming member 111, that corresponds to a large space (discharge chamber 110) in a direction orthogonal to the axis L of the drive shaft 105, cannot be directly clamped by the cylinder block 101, 102 and the housing 103, 104. In consequence, each sheet-like member is likely to float up on the center side. Particularly because the substrate 116, that functions as the base portion for allowing the discharge valve 115 to undergo deformation as a reed valve, cannot be retained under a suitable condition inside the valve/port-forming body 111, deformation of the discharge valve 115 does not occur in a stable way.
The piston type compressor having the construction described above is not free from the problem of vibration and noise that occur in the piping arrangement of the external refrigerating circuit due to pressure pulsation of the discharge refrigerant gas. A muffler chamber 118 is formed in an outer profile portion of the cylinder block 101, 102 to solve this problem. The discharge refrigerant gases from the front and rear side discharge chambers 110 join each other in the muffler chamber 118. The muffler chamber 118 exhibits its muffler function to damp the pressure pulsation and then discharges the gas to the external refrigerating circuit. To improve the effect of damping the pressure pulsation of the discharge refrigerant gas, the capacity of the muffler chamber 118 must be increased, resulting in an increase in the size of the compressor.
Considering specifically the retaining portion 117 of the rear housing 104, a space 119 exists inside the retaining portion 117. To reduce an increase in the weight of the compressor, this space 119 is formed as the retaining portion 117 and is shaped in the ring-like form to correspond to only the outer peripheral portion of the substrate 116. In other words, as the necessity for providing the retaining portion 117 is not very high, the space 119 is formed on the rear housing 104 and the space 119 is a dead space that uselessly occupies the inside of the retaining portion 117.